CARRYING Capacity
Teacher’s Instructions:
1) Hand out the page with the pictures on it (page 7) and allow
students time to interpret it
2) Based on the information conveyed in the pictures, have the
students develop a definition for carrying capacity.
3) Based on their definition of carrying capacity, have the
students determine the factors on which carrying capacity depends.
4) Provide each student with the rest of the handout (pages 2-4)
Read through it together to have the students determine if their
definition for carrying capacity and the factors on which it depends
is appropriate.
5) Go over what the graph of a population at its carrying capacity
looks like. Emphasize that a population fluctuates around it’s
carrying capacity.
6) Ensure that all students realize that the carrying capacity is
the maximum number for a certain population and that populations do
not need to be at their carrying capacities to be stable.
number
carrying capacity
fluctuations
time
7) Have the students answer the questions in the handout.
8) Correct the questions (answer key on pages 5 and 6).
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CARRYING Capacity
Objectives:
- be able to describe the carrying capacity of an ecosystem
- learn some definitions for carrying capacity
Key Terms:
- typically: relating to or representing something
- ecosystem: a system of interacting organisms and their nonliving environment
- equilibrium: stable, balanced or unchanging system
- fluctuate: to rise and fall as if in waves
TASKS:
- look at the carrying capacity picture called “The Full
Bucket”
- interpret it the best you can and create your own definition
of carrying capacity
- determine the factors on which carrying capacity depends
- determine if your definition for carrying capacity is
appropriate
- read the notes and answer the questions on pages 4 and 5
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CARRYING Capacity
Notes:
Carrying capacity is typically expressed as the number of
animals of a certain type which can be supported in an ecosystem.
Carrying capacity may be seen as an equilibrium or balance.
However, the carrying capacity for many species is always changing
due to various factors.
The carrying capacity of an ecosystem depends on three factors:
1) the amount of resources available in the ecosystem
2) the size of the population
3) the amount of resources each individual is consuming
Carrying capacity can also have a broader meaning. It can be
defined as the number of living things (plants and animals) any
area of land or water can support at any one time. Different
organisms will have different carrying capacities in the same area.
Thus, the carrying capacity of an ecosystem affects everything that
lives in it.
The populations of most living things tend to fluctuate
naturally around a certain level. That level is the carrying
capacity. The following is a graph of a population at the carrying
capacity of its ecosystem.
number
carrying capacity
time
CARRYING Capacity
Questions: (20)
1) Write your own definition of carrying capacity. (2)
2) On what does a carrying capacity depend? (3)
3) Can you think of other factors that may affect a carrying capacity? (2)
4) Refer to the following statement when answering the next questions. (4)
“The carrying capacity of this lake equals 150 minnows.”
a) Can less than 150 minnows live in this lake?
b) Can more than 150 minnows live in this lake?
c) Let’s say that there are 140 minnows in this lake when the
amount of resources in this lake decreases and the carrying capacity
drops from 150 to 100 minnows. What will happen to this minnow
population? Why will this happen?
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CARRYING Capacity
5) Refer to the following graphs for the next set of questions. (9)
Graph B
300
250
250
number
number
Graph A
300
200
150
200
150
100
100
50
50
1
2
3
5
4
year
6
7
1
2
3
5
4
year
6
7
FOR GRAPH A:
a) What is the carrying capacity (approx.)?
b) Approximately during which year did this population reach the
carrying capacity of its ecosystem?
c) About how many years did it stay at the carrying capacity?
FOR GRAPH B:
a) What are the carrying capacities of this graph?
b) How many years did this population spend at the first carrying
capacity?
c) During which year did it reach the next carrying capacity?
d) Which carrying capacity is more stable?
Why do you think so?
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CARRYING Capacity
Answer Key: (20)
1) Write your own definition of carrying capacity. (2)
Answers will vary.
2) On what does a carrying capacity depend? (3)
Carrying capacity depends on the amount of resources available,
the size of the population and the amount of resources each individual
is consuming.
3) Can you think of other factors that may affect a carrying capacity? (2)
Answers may vary. Some examples include: natural disasters, human
activities, weather, temperature, etc.
4) Refer to the following statement when answering the next questions. (4)
“The carrying capacity of this lake equals 150 minnows.”
a) Can less than 150 minnows live in this lake?
Yes
b) Can more than 150 minnows live in this lake?
No
c) Let’s say that there are 140 minnows in this lake when the
amount of resources in this lake decreases and the carrying capacity
drops from 150 to 100 minnows. What will happen to this minnow
population? Why will this happen?
This minnow population will decrease to at least 100 minnows.
This will happen because the carrying capacity has decreased due to
one of the following factors: fewer resources available or a larger
population.
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CARRYING Capacity
5) Refer to the following graphs for the next set of questions (9).
Graph B
300
250
250
number
number
Graph A
300
200
150
200
150
100
100
50
50
1
2
3
5
4
year
6
7
1
2
3
5
4
year
6
7
FOR GRAPH A:
a) What is the carrying capacity (approx.)?
250
b) Approximately during which year did this population reach the
carrying capacity of its ecosystem? year 3
c) About how many years did it stay at the carrying capacity? 4
FOR GRAPH B:
a) What are the carrying capacities of this graph?
200 and 100
b) How many years did this population spend at the first carrying
capacity? 2
c) During which year did it reach the next carrying capacity? year 4
d) Which carrying capacity is more stable? Why do you think so?
The second one because the population is more stable at it
(it stayed at the second carrying capacity longer).
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CARRYING Capacity
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